Pulp refining system and apparatus

ABSTRACT

A pressurized refining system characterized in a preferred embodiment by a refiner case consisting in the main of two mating parts forming a shell-like housing enclosing a pair of discs both of which are rotatable, one relative to the other, one of said case parts being simply retractable relative to the other and there being means sealing the shell at the joint defined by the interengagement of the parts in the relatively closed position thereof. The refiner features an environment for and a relationship of the refining discs enabling an improved method of refining fibrous materials particularly under a pressurized condition wherein cutting and abrading is minimized and the fibers are distinctly separated individually and in bundle form so as to preclude unnecessary damage and reduction in their quality and length.

United States Patent [191 Steiniger Oct. 16, 1973 1 PULP REFINING SYSTEM AND APPARATUS [75] Inventor: Herman W. Steinig er, Springfield,

Ohio

[22] Filed: Sept. 23, 1971 {211 App]. No.: 182,945

Related U.S. Application Data [63] Continuation of Ser. No. 495,782, Oct. 14, 1965,

1,146,030 7/1915 Snyder 241/251 1,614,409 l/l927 Surtees 241/251 X 2,931,586 4/1960 Messing 241/245 X Primary Examiner-Granville Y. Custer, Jr. Attorney-Jerome P. Bloom [5 7] ABSTRACT A pressurized refining system characterized in a preferred embodiment by a refiner case consisting in the main of two mating parts forming a shell-like housing enclosing a pair of discs both of which are rotatable, one relative to the other, one of said case parts being simply retractable relative to the other and there being means sealing the shell at the joint defined by the interengagement of the parts in the relatively closed position thereof. The refiner features an environment for and a relationship of the refining discs enabling an improved method of refining fibrous materials particularly under a pressurized condition wherein cutting and abrading is minimized and the fibers are distinctly separated individually and in bundle form so as to preclude unnecessary damage and reduction in their quality and length.

23 Claims, 4 Drawing Figures PATENTEDHBHB ms 3.765313 SHEET 10F 2 BY 75 M ATTORNEY PULP REFINING SYSTEM AND APPARATUS This application is a continuation of applicant's application for United States Letters Patent Ser. No. 495,782, filed /14/65, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to double disc refiners, and particularly to systems and apparatus for operating such refiners in a pressurized environment. Moreover, it enables improvements in refining processes, as will be further described.

In the prior art there has been some allegedly pressurized disc refiners and refining, for example such as exhibited in US. Pats. to Lowgren et al., No. 2,396,587, Asplund et al., No. 2,145,851 and Beveridge et al., No. 2,425,024. The refiner of these patents, known in the trade as single disc refiners, include one rotatable disc forming a cutting surface opposing a fixed abrading surface, between which surfaces fibrous materials are caused to move for refining. Through the many, many years of use of such refiners for wood refining their products have been distinguished by non-uniform particles, short fibers and cut fibers, the whole miminizing the quality of any end product in which they may be incorporated. Moreover, the allegedly sealed environment of refining has been created in such single disc refiners by forming a feed channel leading directly to the single rotating disc, in which channel the feed material is formed as a plug. This dictates a tearing action on the fed material as the face of the roataing disc is pressurized by the fed material, all contributing to limited quality of the defiberized material form.

There has been a US. Pat. No. 1,666,640 which issued in 1928 in which it was proposed to have relatively opposed disintegrating plates including projected teeth which were interdigited and arranged that there was required to be a forced discharge of disintegrated material in a zig-zag path. Per this patent, material to be disintegrated is delivered under pressure, this being necessary due to the tortuous path followed by the material between the disintegrating discs and in discharge. Here while there is pressure on the material while being fed, once delivered through the fine openings from the disintegrating discs, this pressure disappears. As a matter of fact suction is dictated at this side of the discs in the housing to enable escape of the distintegrated material.

Thus the prior art is distinguished by an absence of a refiner which is fully pressurized and which utilizes double revolving discs for achieving long, strong and high quality fibers which are not characteristically cut, disintegrated or abraded.

SUMMARY OF THE INVENTION The present invention is not only the first to enable distinctive extraction of fibers from raw material so as to issue them in many cases in close to original form, but provides improvements in refining casings and systems. The whole is directed to simplifying necessary apparatus for refining and enabling of optimal efficiency thereof in use and maintenance.

A primary object of the invention is to provide a double disc refiner unit including a case structure so constructed to render it economical to fabricate, more efficientand satisfactory in use, adaptable to a wide variety of application and unlikely to malfunction.

A further object of the invention is to provide improvements in refiner structure, particularly double disc refiners, which may be pressurized and in a pressurized condition utilized in an improved refining process having particular application to fibrous pulp materials.

Another object of the invention is to adapt double disc refiners to operate under pressure whereby in the treatment of fibrous material to enhance the ability of the refiner to produce singular fibers of optimal length and quality.

Another object of the invention is to enable a double revolving disc refiner to carry out its operations under selected environmental conditions of temperature and pressure, as for example under conditions prevailing in a digester located upstream of the refiner in relation to the movement of fibrous material in a pulping or like system.

A further object of the invention is to provide a pressurized case for a double disc refiner serving the dual purposes of a means to direct material for refining to and from the discs and of a pressure vessel.

A still further object of the invention is to provide a simple case for a double disc refiner which may be readily sealed against loss of pressure from the case during refiner operation yet adjusted to an open position for ready access to the discs for changing plates or other service requirements.

A still further object of the invention is to provide a refiner case of simplified two-part construction.

Still another object of the invention is to provide a pressurized refiner case of such simplified construction that a part thereof may be separated from other parts of the case for servicing of the discs without the necessity of disturbing either the inlet or the outlet connection.

An additional object of the invention is to provide improvements in refining systems whereby raw fibrous materials can be reduced quickly and effectively to basic constituent parts enabling usage thereof in producing fine quality hard boards, papers and the like and in an economical manner.

With the above and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents. 1

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

FIG. 1 is a fragmentary view in longitudinal section, partly diagrammatic, of a pressurized double disc refiner in accordance with the first illustrated form of the invention;

FIG. 2 is a view similar to FIG. 1, at a reduced scale, showing an alternate form of the invention;

FIG. 3 is a partly diagrammatic view of a pulping system utilizing a refiner in accordance with the instant invention; and

FIG. 4 is the system of FIG. 3 viewed from a position at right angles to that shown in FIG. 3.

Like parts are indicated by similar characters of reference throughout the several views.

A pulping system of the kind to which this invention relates may comprise a number of treatment or material handling stations. These may include, as shown in FIG. 3, an open conveyor feeder advancing fibrous material, for example wood chips or plant stock. In a raw, or partly treated condition the fibrous material drops by gravity into a rotary valve unit 11 interposed between the feeder and a digester 12. The valve device 11 may assume a conventional form, as for example as shown in the US. Pat. to Greaves et al., No. 2,816,693 dated Dec. 17, 1957. It thus incorporates a rotary valve element providing peripheral cavities conducting material through the valve device under conditions precluding pressure fluid escape thereby. Such rotary element is driven by a motor 13 operating through belt means 14.

The digester 12 is supplied with steam, as through a pipe 15, in a manner to maintain the interior thereof under conditions of relatively elevated temperature and pressure. Chemical liquors similarly may be introduced into the digester to assist in the cooking process wherein cohesive substances binding the fibres of the wood chips or plant stock together are softened in a manner to loosen the fibres for subsequent separation. In the illustrated instance the fibrous material is advanced through the digester by suitable feed means operating from a shaft 16 rotatably driven from motor means 17. The steamed and chemical impregnated fibrous material leaves the digester 12 by way of an outlet duct 18 discharging into a downspout 19, the latter connecting at its lower end to the inlet chute 21 of a refiner case 22. The latter provides an enclosure, as will be seen, for double revolving discs comprising the principal operating elements of a refiner 23.

The downspout 19 has a Y configuration with the lower end connecting to chute 21 and one upper arm connecting to digester 12. The other upper arm 19' aligns with chute 21 and may have installed therein a feed screw 20, externally driven and helping to move materials from digester 12 to inlet chute 21. Suitable cover means closes the arm 19' and is constructed to permit passage of the feed screw shaft therethrough.

Further comprised in such refiner are longitudinally spaced apart motors 24 and 25 driving respective shafts 26 and 27 which extend into the case 22, in a manner to be more specifically described, and mount respective refining discs thereon. The fibrous material passes through the refining station as represented by the refiner 23 and discharges therefrom through a duct 28 to another rotary valve device 29. This device, operated by a motor 31 through a belt drive 32, is in the illustrated instance like the valve device 11. It accordingly also incorporates a rotary valve element providing peripheral cavities conducting material through the valve device under conditions precluding pressure fluid escape thereby. Beyond valve device 29 the treated fibrous material is advanced through a duct 33 to a subsequent treatment station, as for example a cyclonic separator. The valve 29 may assume other forms suitable to a controlled discharge of material and steam. For example a Z body valve of Fisher Controls may be substituted for the one shown.

The valves 11 and 29 have the effect of segregating the digester l2 and the refiner 23 from the balance of the system. Accordingly, pressure and temperature conditions established in the digester 12 pervade the segregated area. The case 22 is thus interiorly pressurized by steam from the digester. Supplemental steam may if desired be supplied directly to the case 22. The

case 22 is sealed, as will hereinafter more clearly appear, so that the work performed by the refining discs within the case is in a pressurized environment.

Due to the size of the described'equipment, and the use made of gravity flow, the different described locations are at different levels, as for example on different floors of the same building. Thus the conveyor feeder 10 is mounted on an uppermost level or floor 34, the digester 12 on a lower level 35 and the refiner 23 on a lowermost floor 36. An intermediate level 37, supporting motor means 17, rests on a support wall 38.

Referring now to FIG. 1, the shafts 26 and 27 of the refiner 23, have what may be termed their inboard ends supported in respective bearing assemblies 39 and 41. The shafts are in an aligned opposing relation and their inner ends are disposed adjacent to one another within the case 22. Secured to the inner end of the shaft 26 is a refining disc 42. In an opposing spaced relation to the disc 42 is a like disc 43 secured to the inner end of shaft 27. ln an annular area of each disc, near the periphery thereof, is a circumferential series of working plates 44. In another and inwardly spaced annular area of the disc 42 is a circumferential series of feed openings 45. An adapter ring 46 is bolted to what may be considered the rear face of the disc 42 and turns in a bearing ring 47. Openings 48 in the adapter ring 46 are aligned with openings 45 and communicate the latter with an inclined feed passage 49 in the aforementioned chute 21. The passage 49 communicates with the previously described downspout 19 leading from digester 12. Accordingly, the digester treated fibrous material, along with steam from the digester, is directed by passage 49 to the openings 45 in disc 42 and thereby between the discs 42 and 43.

In the operation of the refiner, the discs revolve, in respectively opposite directions, and the fibrous material is constrained to move radially outward into the area occupied by plates 44. The plates 44 on the respective discs are spaced from 0.04 to 0.10 inches, depending on the particular application, and are preferably spaced between 0.04 and 0.08 for fibrous materials in accordance with the present invention as here described. In application to waste paper (asphalt dispersion), for example, the spacing may be as much as 0. l0 inches. This degree of spacing prescribed is contrasted to the plate separations of from 0.01 to 0.03 inches required and used in conventional refiners of the type described. Due to the spacing as provided by the invention, as the fibrous material is constrained to move outward on the plates 44, the plates produce a rapid rolling of fiber bundles and a gentle separation of the fibers under the influence of centrifugal force. The flow of the fiber bundles is fast and the separation into their individual components is just as rapid. The result is enhanced by the fact the widely spaced discs operate in a pressurized environment. An optimal environment will be further described.

In any event, the resultant fibers in the example illustrated will be much longer and stronger than would result in a conventional disc refining operation on the same material. As used in end products the visual and surface texture of said products is much finer, smoother and less coarse than heretofore imagined possible. Moreover, processing for end product use is minimized.

As a result of the pressure and gravity influences in the refiner 23, the material which is peripherally discharged from between the refiner plates moves to a lower part of the case 22 to an exit or outlet opening 51, communicating through tubular adapter means 52 with the aforementioned valve 29. There are peripherally mounted disc wipers 50 on the disc 43 which propel material issuing from between the discs along the periphery thereof and toward the outlet 51.

Steam pressurization in the double disc mill as provided affords substantial advantages in reference to power consumption and production of the fibers of most desirable quality. The combination of pressure and temperature produced in the refiner weakens the bonding material in wood, for example, to the extent the fibers are easier to separate under the influence of the mechanical action exerted by the plates 44 on the refiner discs. The pressurization in an improved refining process lends ability to the refiner to operate with the opposing sets of plates 44 in an optimally spaced relation. It is noted that the spacing of the plates permit the fibers to be loosened rather than separated by abrasive and cutting action. As will be further described in reference to an optimal pulp refining process in accordance with the invention, the discharge fibers are well formed, relatively unscarred and of good length.

The case 22 of the invention is constructed to sustain selected pressures and temperatures, as for example pressures on the order of 100 lbs. to 150 lbs. per square inch and temperatures of as much as 340 F. It is, moreover, most simply constructed and readily separable into component parts, facilitating the replacement of worn plates 44.

In the refiner of the invention shown in FIG. 1 the case is comprised essentially of two respectively integral parts 53 and 54 which originally, for manufacturing expediency, can be fabricated of multiple elements. In such instance, however, the elements are welded together to form an integrated unit so that the respective parts will here be considered as though made out of a single piece of material. Part 53 has the configuration of a flat planar disc terminating at its periphery in a projected flange 55. In the center of the part 53 is an opening 56 receiving the above mentioned ring 47. Counterbores in the outer surface of the part 53 provide a seat for the discharge end of chute member 21 which may be considered integrated with the part 53. The shaft 26 passes through the chute 21 which is in a closely surrounding relation thereto, and axially through opening 56 to the case interior as before described. The chute 21 provides a recessed boss 57 in which is packing means 58 positioning about shaft 26. Retained in place by collar means 59 on the shaft 26, the packing means 58 inhibits a loss of pressure from case 22 along the shaft.

The plate 53 is thus mounted on one side of the pair of rotating discs 42 and 43. On the other side thereof, and in a surrounding relation to the shaft 27, is the second part 54. This part is generally dish shaped in configuration, comprising a plate portion 61 generally parallel to the plate 53 and a longitudinally projected peripheral cup portion 62. The latter extends toward the plate 53 and terminates in an upstanding flange 63 parallel to flange 55. In an assembled or closed position of the parts 53 and 54 the flanges 55 and 63 contact one another and are releasably secured together, as by bolts 64. Further, the projected periphery of part 54 achieves a telescoping relation to the periphery of part 53 and at the inner portion of the base of flange 55 confines a sealing ring 65. An angular cut-out in the projected periphery of portion 62, at the base of flange 63, defines a groove 66 receiving the sealing ring 65. The arrangement, it will be understood, is one whereby a simple mating of the flanges and 63 and a drawing down of the bolts 64 serves to compress the ring 65, effectively and simply sealing the joint between the parts 53 and 54 against the escape of pressure from the case interior by this route. The shaft 27 passes through a center opening in the part 54 where a cylindrical sleeve 67 is installed. Sleeve 67 is attached to the part 54 by bolts 68 and in conjunction with collar means 69 on the shaft 27 confines packing means 71 sealing against an escape of pressure from the interior of case 22 along such shaft.

The line of separation between the parts 53 and 54, as defined by the point of mating contact between the flanges 55 and 63, accordingly is in a vertical plane to one side of the pair of discs 42 and 43. The outlet 51 from the case 22 is, however, located in the projected periphery 62 of part 54 and is approximately aligned with the line of separation between the discs 42 and 43.

That end of the refiner most adjacent motor 25, bearing assembly 41 and shaft 27 may be termed the control end. It is from this end that shaft 27 may be conventionally adjusted in a longitudinal sense (by means not here shown) to vary the clearance between opposing sets of plates 44. Similarly, it is to this end of the refiner that dish shaped part 54 may be retracted from part 53 to expose the discs 42 and 43 for access thereto. The part 54 normally occupies what may be considered a closed position as illustrated. To achieve an open position of the case, the bolts 64 alone or with bolts 68 are withdrawn and the part 54 shifted rearwardly or in a direc tion away from part 53. The means utilized for shifting may be manual or otherwise and are not detailed since in and of themselves they form no part of the present invention. Upon return of the part 54 to a closed position the bolts are reinstalled and tightened, the sealing ring is recompressed and the interior of case 22 is again sealed off in this most simple manner.

Insert fittings 72 and 73 are installed in the part 54 for inserting socket wrenches for the installation or removal of plate bolt nuts.

The simplicity of the refiner structure is believed obvious.

An alternate form of the invention shown in FIG. 2 schematically shows discs 74 and 75 corresponding to discs 42 and 43. Shafts 76 and 77 corresponding to shafts 26'and 27 mount the respective discs 74 and 75 within a case 78. Sealing assemblies 79 and 81 are structurally like corresponding assemblies in the FIG. I embodiment and similarly inhibit an escape of pressure fluid from within the case 78 along the respective shafts.

The embodiment of FIG. 2, likethe embodiment of F IG. 1, provides a case of two part construction which is simply and effectively sealed. In this instance, however, both parts 82 and 83 are generally complementary and dish or cup shaped and have projected peripheries of asymetrical configuration. Thus, and referring to part 82, the projected periphery 84 thereof has a progressively changing slope between diametrically opposed positions in such manner as to have a maximum projected length in one circumferential area and to have a minimum length in a diametrically opposed circumferential area. The part 83 is complementarily constructed substantially like the part 82 and in the assembly of the case the parts are rotatively positioned to lie in a complementary position to one another. The joint or line of separation between the parts accordingly is on the bias or diagonal, extending in inclined fashion in intersecting relation to the plane of the line of separation between discs 74 and 75. A projecting peripheral portion 85 of the part 83 accordingly is disposed in a diametrically opposed relation to projecting peripheral portion 84 of part 82. The opposed peripheral portions are formed with respective flanges adapted to be drawn into an interfitting or abutting contact by bolts 86. In the abutting, flanged end of peripheral portion 85 is a groove 87 having an O-ring 88 installed therein. Under the clamping pressure applied by tightening of bolts 86 the O-ring 88 is compressed and the joint or line of separation between the parts 74 and 75 of the case effectively is sealed. By loosening the bolts 86 the part 83 may be retracted relatively to the part 82 for access to the discs 74 and 75, in the same manner that part 54 of the FIG. 1 embodiment is retracted. In the instance of FIG. 2, however, both inlet chute 89 and outlet duct 91 are installed in or formed integrally with the part 82. Accordingly, retraction of the part 83 involves no separation of the inlet and outlet fittings which could create problems in re-creating the sealed relation of the parts.

The arrangement of the casing is one to place the long portion of projected periphery 84 of part 82, containing outlet 91, in underlying relation to the discs 74 and 75. Correspondingly, therefore, the long portion of projected periphery 85 of part 83 overlies the discs and when withdrawn readily exposes the discs for access to the plates carried thereby.

The foregoing describes, in preferred forms, the system and apparatus of the invention, particularizing the double disc refiner structure capable of being simply and effectively installed to produce a pressurized refiner unit of unique character. Such a unit has been tested and can be pressurized and effectively operate as described with its refiner discs spaced a significant degree more than ever before contemplated in similar type units. It is of course readily obvious that the very simplicity of the refiner case structure and its inherent advantages for effecting and maintaining a seal provides a significant part of the present invention.

The system in accordance with the invention further enables improved refining processes particularly in reference to the fibrous pulp-type materials. For example, in processing or defiberizing fibrous pulp material, the invention contemplates a spacing of the refiner plates from 0.04 to 0.08 inches, a pressure in the refiner case, for example, of 100 to 150 p.s.i. and a temperature condition in the range of 320 to 340 fahrenheit.

With the conditions as described, on introducing fibrous pulp material to the case 22 and movement thereof to flow between the refining discs, the spacing of the refiner plates thereon is such that the pulp is rolled into fiber bundles, the rolling being rapid and producing a gentle separation of the fibers under the influence of centrifugal force created in the counterrotation of the discs. The separation is facilitated by the temperature and pressure conditions which influence a rapid softening of the bonds between the fibers. The flow through period is rapid. Accordingly, the fibers have a short dwell period in the refiner. The fibers which exit from between the peripheral portion of the opposed refining plates are long and of considerable strength. With the enabling of the wide spacing of the refiner plates one precludes abrasion and cutting which destroys the potential quality of the fibers.

Thus, refining in the double disc refiner of the invention under the conditions specified produces generally improved and highly desirable products. A side effect of this optimum processing of materials as enabled in the pressurized double disc refiner is that the load on the refiner discs bearing the refiner operation is minimal. The power savings as a result of this condition are significant.

Tests and subsequent commercial use of the invention commercially has proven that the invention has enabled that there be produced directly from raw material, in a single pass, fibers in individual and bundle form wherein their natural characteristics are retained to a substantial degree, enabling, for example, unique and fine hardboard and other fiber board end products wherein the usual cut, chop and shives which are distinctive of products of prior known refining systems is not evidenced. Take note that in spite of the wide range of prior art knowledge, long known to experts in the art, no one heretofore achieved anything approaching the fiber product enabled by the invention.

It is observed that one should not overlook that the simplicity of the illustrated case structures achieves not only an economy of fabrication for double disc refiners but an economy in use and servicing thereof.

Experience has indicated that the invention enables the production of a uniform fiber with an excellent length to width ratio from wood chips, sawdust, shavings and mixed scrap or combinations and that such a material cannot be made of the same feed in either a pressurized single revolving disc type machine or a con ventional single or double revolving disc refiner.

Further experience has established that the fibers discharged from the invention system have due to the nature of the action thereon a coating of natural wood binder. When such fibers are felted into a mat and hot pressed, the coating acts the same as a glue or synthetic resin binder. In certain types of products such as medium density board (42 lbs./cu.ft.), additional strength is obtained by reason of this coating. The invention is capable of converting more kinds or forms of wood or wood scrap into better stock than is obtainable in any existing way.

The invention has been found to be particularly important to ecology from the standpoint it preserves .within the apparatus and the materials processed thereby the chemicals normally extracted and discharged to the environment. Accordingly, it eliminates the delivery of offensive materials and odors to the atmosphere and streams. The invention system does in fact enable the utilization of all chemical constituents of the pulp processed therein.

From the above description it will be apparent that there is thus provided a device of the character deshown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect, and the invention is therefore claimed .in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described my invention I claim:

1. Refining apparatus comprising means defining a pressurized segment of a refining system, including a shell-like refiner case comprised of mating separable parts sealed together to form a pressure vessel, a pair of refiner discs, means mounting said discs within said case in a directly opposed relation, spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other, said case being constructed and provided with means for operation of said discs therein under conditions where the internal pressure ranges up to about 150 psi. above atmospheric pressure, one of said case parts being separable therefrom to expose peripheral portions of said discs for access thereto as and when required, said pressurized segment including valve means for directing fibrous material to said segment and to said discs in a continuing flow while maintaining a pressure seal at the entrance to said segment, said discs being arranged to operate on said fibrous material to loosen and separate therefrom, in a single pass, individual fibers in a condition in which they maintain, to a substantial degree, their natural physical characteristics, and said pressurized segment further includes valve means for controlling the discharge of the refined material from said case while maintaining a pressure seal of said segment.

2. Refining apparatus as in claim 1 wherein said pressurized segment includes a digester for subjecting the fibrous material to treatment under conditions of elevated pressure and temperature immediately in advance of said refiner discs and there being means within said digester for conducting said fibrous materials therethrough to said discs.

3. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, said case being comprised of mating separable parts sealed together to form a pressure vessel for said discs one of which parts is separable to expose peripheral portions of said discs for access thereto, means mounting said discs within said case in a directly opposed relation spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other,

means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while maintaining a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, said case including two interengaging opposing parts encompassing peripheral portions of said discs, individual shaft means providing means for mounting said discs, said one of said parts of said case being retractable to expose peripheral portions of both said discs and said shaft means being projected from said case and having sealing means thereabout in which they bear at the portions thereof projected through said case, characterized by said case being comprised of two parts, a first part being on one 'side of said pair of discs in a surrounding relation to one of said shaft means and a second said part being on the other side of said pair of discs in a surrounding relation to the other one of said shaft means, said parts having a relatively closed position in which portions thereof interfit, and said second part being relatively retractable along said other shaft means while retaining an assembled relation thereto whereby to cause said parts to assume an open position peripherally exposing said discs for access thereto, and means sealing said case at the joint defined by said interfitting portions and relative to said shaft means whereby to allow interior pressurization of said case in the closed position of said parts thereof.

4. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, said case being comprised of mating separable parts sealed together to form a pressure vessel for said discs one of which parts is separable to expose peripheral portions of said discs for access thereto, means mounting said discs within said case in a directly opposed relation spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while'maintaining a a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, a digester for subjecting the fibrous material to treatment under conditions of elevated temperature and pressure, said means for providing a pressure seal of said case including means isolating said digester and said refining discs to establish within said shell-like case and said digester asubstantially common pressurized high temperature environment and provide for the delivery of the fibrous material in fragment form to said environment and the discharge of the resulting fiber product from said environment, and means for conducting said fibrous materials from said digester to and through said case to said discs under conditions of common elevated temperature and pressure and said case forming the sole enclosure for said discs and serving the dual func tion of a pressure vessel and of a means to collect and discharge refined fiber material.

5. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, means mounting said discs within said case in a directly opposed relatively spaced relation to each other and said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while providing a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, and said case being comprised of mating separable parts sealed together to form a pressure vessel, said separable parts being free of said discs and at least one being relatively retractable to peripherally expose said discs for access, characterized by said case being comprised of two mating separable parts one of which includes said case inlet and said case outlet.

6. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, means mounting said discs within said case in a directly opposed relatively spaced relation to each other and said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving fiow while providing a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, and said discs having means defining relatively opposed working surfaces which are fully spaced and have a free space therebetween of not less than 0.04 inches.

7. Apparatus as set forth in claim 6 characterized by said discs having their working surfaces spaced apart in a range from about 0.04 inches to about 0.10 inches.

8. Apparatus as set forth in claim 6 characterized by said discs having means defining relatively opposed working surfaces which are separated by a free space in the range of approximately 0.04 to 0.08 inches.

9. Apparatus as set forth in claim 8 characterized by means to establish within said case pressures on the order of 100 to 150 psig.

10. In the art of pulping and refining, a double disc refiner including a pair of opposed rotatable discs, plural interengaged parts defining a case enclosing said discs, said case having an outlet for worked material, one of said parts being stationary and another being relatively movable to expose said discs, chute means on said stationary part having an inlet passage for material to be worked opening through said stationary part and communicating through one of said discs with the space between said discs, individual opposing shafts, each mounting one of said discs, the shaft mounting said one disc having a bearing in said chute means and extending beyond said bearing through said inlet passage and into said case, and means for sealing said case to allow working of the contained material under conditions of selected pressure, including means in said bearing for effecting a seal around said shaft.

11. A double disc refiner according to claim 10, wherein said inlet passage terminates in a chamber intermediate said bearing and said one disc, said stationary part having an opening for inflow of material from said chamber, said one disc being open to admit inflowing material to move between said discs, said shaft projecting through said chamber and through said opening and being undersized relative to said opening for free flow of material thereby.

12. A double disc refiner according to claim 11, wherein the removable part of the case is adjustable to peripherally expose the discs for access.

13.,A double disc refiner according to claim 12, wherein the removable part of the case has the outlet formed integral therein.

14. A double disc refiner according to claim 12, wherein the stationary part of the case has the outlet formed integral therein.

15. In the art of pulping and refining, a double disc refiner comprising a pair of opposed relatively rotatable discs, a case in enclosing relation to said discs and providing a peripheral outlet opening substantially in the line of separation between said discs, said case comprising first and secondparts on opposite sides of said pair of discs, each having a dish-like asymmetrical complementary configuration and rotatively positioned in complementary fashion to define a line of separation therebetween diagonal to the line of separation between said discs, said outlet opening being in a projected peripheral portion of said first part in underlying relation to said discs, a corresponding projected peripheral portion of said second part overlying said discs, sealing means installed between said parts in the 0 line of separation therebetween inhibiting loss of pressure from within said case, and shafts extending into said case through respective parts mounting respective discs thereon.

16. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting respective discs, opposing interengaging parts defining a case enclosing said discs, said case including a first part on one side of said pair of discs in a surrounding relation to one of said shafts and further including a second part on the other side of said pair of discs in a surrounding relation to the other one of said shafts, said parts having a relatively closed position in which portions thereof interfit and said second part being relatively retractable to cause said parts to assume an open position peripherally exposing said discs for access thereto, means for sealing said case at the joint defined by said interfitting portions and relative to said shafts whereby to allow interior pressurization of said case in the closed position of said parts thereof, and means for admitting pulp to and discharging it from said case, said last named means including an inlet formed in the said first part of said case and an outlet formed in the said second part of said case, said outlet being disposed substantially in line with the separation of said discs, said second part being dished to present a longitudinally projected periphery, said outlet being formed in said projected periphery.

17. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting respective discs, opposing interengaging parts defining a case enclosing said discs, said case including a first part on one side of said pair of discs in a surrounding relation to one of said shafts and further including a second part on the other side of said pair of discs in a surrounding relation to the other one of said shafts, said parts having a relatively closed position in which portions thereof interfit and said second part being relatively retractable to cause said parts to assume an open position peripherally exposing said discs for access thereto, means for sealing said case at the joint defined by said interfitting portions and relative to said shafts whereby to allow interior pressurization of said case in the closed position of said parts thereof, and means for admitting pulp to and discharging it from said case, said last named means including an inlet and an outlet both in said first part of said case, said outlet being disposed substantially in the line of separation of said discs, said first part having a longitudinally projected peripheral portion in which said outlet is formed.

18. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, a case for said discs, said case consisting of a pair of mating parts separable from one another to provide access to said discs, and means in connection therewith for sealing the case so provided, both said pair of parts being cup-shaped and having mating edges which meet on a bias.

19. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, a case for said discs, said case consisting of a pair of mating parts separable from one another to provide access to said discs, and means in connection therewith for sealing the case so provided, one of said parts including both an inlet to andan outlet from said case, and adapted to be bridged by said sealing means.

20. lnthe art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting the respective discs for individual and relative drive thereof, a shell-like case enclosing said discs and spaced to be free thereof, said case including readily separable parts having a relatively closed position in which portions thereof interfit, at least one of said parts being separable to freely retract and provide access to peripheral portions of said discs, sealing ring means installed between said interfitting portions to be compressed in a closed position of said parts and means for admitting to and discharging pulp from said case and for establishing and maintaining said discs in a sealed pressurized environment, said discs having spaced working surfaces adapted for a rolling passage therebetween of fibrous materials and a pulling free of individual fibers and fiber bundles from surface portions of such materials in a manner to inhibit cutting and abrading thereof.

21. Apparatus as in Claim 20 characterized by said admitting means including an inlet chute integrally connected to one of said parts opening to an area within said case to the rear of one of said discs, said one 'of said discs having feed passages therethrough which open to the space between said discs adjacent their centers and said chute having therein means for expediting the free flow of material to and through said feed passages.

22. Apparatus according to Claim 20 characterized in that one of said parts has an outlet for discharge of refined material from said case disposed approximately in line with the separation of said discs and both said parts being dish shaped in a symmetrical complementary configuration, the line of separation between said parts being inclined to and intersecting the plane of the line of separation of said discs.

23. Apparatus according to claim 20 characterized in said case being comprised of two parts having projected peripheries of asymmetrical complementary configuration, one of said parts including an outlet opening for discharge of refined material and the other of said parts which is retractable having a projected peripheral portion in diametrically opposed relation to said outlet. 

1. Refining apparatus comprising means defining a pressurized segment of a refining system, including a shell-like refiner case comprised of mating separable parts sealed together to form a pressure vessel, a pair of refiner discs, means mounting said discs within said case in a directly opposed relation, spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other, said case being constructed and provided with means for operation of said discs therein under conditions where the internal pressure ranges up to about 150 p.s.i. above atmospheric pressure, one of said case parts being separable therefrom to expose peripheral portions of said discs for access thereto as and when required, said pressurized segment including valve means for directing fibrous material to said segment and to said discs in a continuing flow while maintaining a pressure seal at the entrance to said segment, said discs being arranged to operate on said fibrous material to loosen and separate therefrom, in a single pass, individual fibers in a condition in which they maintain, to a substantial degree, their natural physical characteristics, and said pressurized segment further includes valve means for controlling the discharge of the refined material from said case while maintaining a pressure seal of said segment.
 2. Refining apparatus as in claim 1 wherein said pressurized segment includes a digester for subjecting the fibrous material to treatment under conditions of elevated pressure and temperature immediately in advance of said refiner discs and there being means within said digester for conducting said fibrous materials therethrough to said discs.
 3. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, said case being comprised of mating separable parts sealed together to form a pressure vessel for said discs one of which parts is separable to expose peripheral portions of said discs for access thereto, means mounting said discs within said case in a dirEctly opposed relation spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while maintaining a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, said case including two interengaging opposing parts encompassing peripheral portions of said discs, individual shaft means providing means for mounting said discs, said one of said parts of said case being retractable to expose peripheral portions of both said discs and said shaft means being projected from said case and having sealing means thereabout in which they bear at the portions thereof projected through said case, characterized by said case being comprised of two parts, a first part being on one side of said pair of discs in a surrounding relation to one of said shaft means and a second said part being on the other side of said pair of discs in a surrounding relation to the other one of said shaft means, said parts having a relatively closed position in which portions thereof interfit, and said second part being relatively retractable along said other shaft means while retaining an assembled relation thereto whereby to cause said parts to assume an open position peripherally exposing said discs for access thereto, and means sealing said case at the joint defined by said interfitting portions and relative to said shaft means whereby to allow interior pressurization of said case in the closed position of said parts thereof.
 4. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, said case being comprised of mating separable parts sealed together to form a pressure vessel for said discs one of which parts is separable to expose peripheral portions of said discs for access thereto, means mounting said discs within said case in a directly opposed relation spaced from each other and from said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while maintaining a a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, a digester for subjecting the fibrous material to treatment under conditions of elevated temperature and pressure, said means for providing a pressure seal of said case including means isolating said digester and said refining discs to establish within said shell-like case and said digester a substantially common pressurized high temperature environment and provide for the delivery of the fibrous material in fragment form to said environment and the discharge of the resulting fiber product from said environment, and means for conducting said fibrous materials from said digester to and through said case to said discs under conditions of common elevated temperature and pressure and said case forming the sole enclosure for said discs and serving the dual function of a pressure vessel and of a means to collect and discharge refined fiber material.
 5. Refining apparatus comprising a shell-like case having an inlet thereto And an outlet therefrom, a pair of refining discs, means mounting said discs within said case in a directly opposed relatively spaced relation to each other and said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while providing a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, and said case being comprised of mating separable parts sealed together to form a pressure vessel, said separable parts being free of said discs and at least one being relatively retractable to peripherally expose said discs for access, characterized by said case being comprised of two mating separable parts one of which includes said case inlet and said case outlet.
 6. Refining apparatus comprising a shell-like case having an inlet thereto and an outlet therefrom, a pair of refining discs, means mounting said discs within said case in a directly opposed relatively spaced relation to each other and said case, means for rotating both said discs through their mounting means, one relative the other, means for providing a pressure seal of said case and including means for delivery of fragments of raw fibrous material to said case and between said discs in a free moving flow while providing a pressure seal of said case, means for maintaining an environment of elevated temperature and pressure within said case and about said discs, said discs being mounted, disposed and formed to roll the raw fragments therebetween to separate the same into individual fibers and fiber bundles in a manner to inhibit disintegration and cutting the individual fiber content of said fragments, and said discs having means defining relatively opposed working surfaces which are fully spaced and have a free space therebetween of not less than 0.04 inches.
 7. Apparatus as set forth in claim 6 characterized by said discs having their working surfaces spaced apart in a range from about 0.04 inches to about 0.10 inches.
 8. Apparatus as set forth in claim 6 characterized by said discs having means defining relatively opposed working surfaces which are separated by a free space in the range of approximately 0.04 to 0.08 inches.
 9. Apparatus as set forth in claim 8 characterized by means to establish within said case pressures on the order of 100 to 150 psig.
 10. In the art of pulping and refining, a double disc refiner including a pair of opposed rotatable discs, plural interengaged parts defining a case enclosing said discs, said case having an outlet for worked material, one of said parts being stationary and another being relatively movable to expose said discs, chute means on said stationary part having an inlet passage for material to be worked opening through said stationary part and communicating through one of said discs with the space between said discs, individual opposing shafts, each mounting one of said discs, the shaft mounting said one disc having a bearing in said chute means and extending beyond said bearing through said inlet passage and into said case, and means for sealing said case to allow working of the contained material under conditions of selected pressure, including means in said bearing for effecting a seal around said shaft.
 11. A double disc refiner according to claim 10, wherein said inlet passage terminates in a chamber intermediate said bearing and said one disc, said stationary part having an opening for inflow of material from said chamber, said one disc being open to admit inflowing maTerial to move between said discs, said shaft projecting through said chamber and through said opening and being undersized relative to said opening for free flow of material thereby.
 12. A double disc refiner according to claim 11, wherein the removable part of the case is adjustable to peripherally expose the discs for access.
 13. A double disc refiner according to claim 12, wherein the removable part of the case has the outlet formed integral therein.
 14. A double disc refiner according to claim 12, wherein the stationary part of the case has the outlet formed integral therein.
 15. In the art of pulping and refining, a double disc refiner comprising a pair of opposed relatively rotatable discs, a case in enclosing relation to said discs and providing a peripheral outlet opening substantially in the line of separation between said discs, said case comprising first and second parts on opposite sides of said pair of discs, each having a dish-like asymmetrical complementary configuration and rotatively positioned in complementary fashion to define a line of separation therebetween diagonal to the line of separation between said discs, said outlet opening being in a projected peripheral portion of said first part in underlying relation to said discs, a corresponding projected peripheral portion of said second part overlying said discs, sealing means installed between said parts in the line of separation therebetween inhibiting loss of pressure from within said case, and shafts extending into said case through respective parts mounting respective discs thereon.
 16. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting respective discs, opposing interengaging parts defining a case enclosing said discs, said case including a first part on one side of said pair of discs in a surrounding relation to one of said shafts and further including a second part on the other side of said pair of discs in a surrounding relation to the other one of said shafts, said parts having a relatively closed position in which portions thereof interfit and said second part being relatively retractable to cause said parts to assume an open position peripherally exposing said discs for access thereto, means for sealing said case at the joint defined by said interfitting portions and relative to said shafts whereby to allow interior pressurization of said case in the closed position of said parts thereof, and means for admitting pulp to and discharging it from said case, said last named means including an inlet formed in the said first part of said case and an outlet formed in the said second part of said case, said outlet being disposed substantially in line with the separation of said discs, said second part being dished to present a longitudinally projected periphery, said outlet being formed in said projected periphery.
 17. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting respective discs, opposing interengaging parts defining a case enclosing said discs, said case including a first part on one side of said pair of discs in a surrounding relation to one of said shafts and further including a second part on the other side of said pair of discs in a surrounding relation to the other one of said shafts, said parts having a relatively closed position in which portions thereof interfit and said second part being relatively retractable to cause said parts to assume an open position peripherally exposing said discs for access thereto, means for sealing said case at the joint defined by said interfitting portions and relative to said shafts whereby to allow interior pressurization of said case in the closed position of said parts thereof, and means for admitting pulp to and discharging it from said case, said last named means including an inlet and an outlet both in said first part of said case, saiD outlet being disposed substantially in the line of separation of said discs, said first part having a longitudinally projected peripheral portion in which said outlet is formed.
 18. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, a case for said discs, said case consisting of a pair of mating parts separable from one another to provide access to said discs, and means in connection therewith for sealing the case so provided, both said pair of parts being cup-shaped and having mating edges which meet on a bias.
 19. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, a case for said discs, said case consisting of a pair of mating parts separable from one another to provide access to said discs, and means in connection therewith for sealing the case so provided, one of said parts including both an inlet to and an outlet from said case, and adapted to be bridged by said sealing means.
 20. In the art of pulping and refining, a double disc refiner including a pair of opposed relatively rotatable discs, individual opposing shafts mounting the respective discs for individual and relative drive thereof, a shell-like case enclosing said discs and spaced to be free thereof, said case including readily separable parts having a relatively closed position in which portions thereof interfit, at least one of said parts being separable to freely retract and provide access to peripheral portions of said discs, sealing ring means installed between said interfitting portions to be compressed in a closed position of said parts and means for admitting to and discharging pulp from said case and for establishing and maintaining said discs in a sealed pressurized environment, said discs having spaced working surfaces adapted for a rolling passage therebetween of fibrous materials and a pulling free of individual fibers and fiber bundles from surface portions of such materials in a manner to inhibit cutting and abrading thereof.
 21. Apparatus as in Claim 20 characterized by said admitting means including an inlet chute integrally connected to one of said parts opening to an area within said case to the rear of one of said discs, said one of said discs having feed passages therethrough which open to the space between said discs adjacent their centers and said chute having therein means for expediting the free flow of material to and through said feed passages.
 22. Apparatus according to Claim 20 characterized in that one of said parts has an outlet for discharge of refined material from said case disposed approximately in line with the separation of said discs and both said parts being dish shaped in a symmetrical complementary configuration, the line of separation between said parts being inclined to and intersecting the plane of the line of separation of said discs.
 23. Apparatus according to claim 20 characterized in said case being comprised of two parts having projected peripheries of asymmetrical complementary configuration, one of said parts including an outlet opening for discharge of refined material and the other of said parts which is retractable having a projected peripheral portion in diametrically opposed relation to said outlet. 